Some great models there, Joel, such as the Ferrari Dino and the battle-scarred Paxton.
As for the white shells in your first post, I tend to agree with Charles and Ron that they'd be Mardave, though your later comment about scale keeps us puzzling.
Anyway, when I posted a similar photo of the Aston shell a year or two ago, our experts agreed on Mardave and we found a couple of contemporary magazine references. Mardave also made a McLaren-Oldsmobile, a Ford GT (presumably GT40) and a Marcos 1800GT. Lister and Maserati were not mentioned, but yours look in the same style.
The Mardaves were in reasonably thick white polystyrene, at first with a gloss finish but then matt for better paint adhesion.
Here's the interior view of the Aston I had. (Don't have the shell now; exchanged it with another SF member.)
I'm delighted to see celebration of vac-formed shells here. I'm glad to still have most of my 1970s builds and have more than a dozen unused that deserve to be used, so I was disappointed when I joined SF to get the impression in the Scratchbuilding forum that they were now scorned.
However, a few days ago I did notice a thread there (active a year or two ago) in which one of the best scratchbuilders was using a vac shell for an F1 car. He was praising it for being thinner than the alternatives, enabling him to fit what he wanted in a well-scaled shell.
They were often out of scale and they have their disadvantages (e.g. race marshall handling, mounting single-seater suspension), but they're a damn sight easier to get a good paint finish on.
It'd be interesting to know how well vac shells sell nowadays - how many vacs v fibreglass at Betta & Classic, for example, though I suppose the f'glass range is smaller.
Pattos has a great range of vacs and they seem quite popular. Some are, well, let's say "plain", but others like the V16 BRM are very detailed.
Rob J